Onychomycosis caused by the environmental mold Neoscytalidium dimidiatum in Colombia, and in vitro antifungal susceptibility evaluation.

Neoscytalidium dimidiatum is a plant pathogen, but can also cause onychomycosis. We compared clinical and epidemiological data of cases of onychomycosis caused by N. dimidiatum and Trichophyton rubrum. We also evaluated the in vitro antifungal susceptibility of N. dimidiatum clinical isolates. It was not possible to establish any statistical differences between groups, except the place of residence and the number of affected nails. The results suggest that onychomycosis caused by N. dimidiatum is clinically similar to that caused by T. rubrum; besides, N. dimidiatum has been shown to have low sensitivity to itraconazole, but high to terbinafine. LAY SUMMARY: Cases of onychomycosis caused by Neoscytalidium dimidiatum were studied and compared to cases of onychomycosis caused by T. rubrum. The individuals affected were adults, and the clinical characteristics were not different between groups; accordingly, mycological diagnosis is mandatory.

ITS rDNA Gene Analysis Versus MALDI-TOF MS For Identification of Neoscytalidium dimidiatum Isolated from Onychomycosis and Dermatomycosis Cases in Medellin (Colombia).

Within the Neoscytalidium genus, N. dimidiatum, N. oculus, N. orchidacearum, and N. novaehollandiae have been recognized. Although these species are frequently found in soil, N. dimidiatum has been identified as an etiologic agent of onychomycosis or dermatomycosis, and N. oculus has been identified as an etiologic agent of an ocular lesion. All these species can be cultured in vitro, but their morphological identification by macroscopic and microscopic traits is difficult and imprecise due to their similarity. In this study, 34 isolates of Neoscytalidium spp. from 32 onychomycosis and two dermatomycosis cases in Medellin (Colombia) were identified at the species level using sequencing of the ITS1+5.8S+ITS2 nuclear rDNA region and MALDI-TOF mass spectrometry (MS). Neoscytalidium dimidiatum strain MUM 17.21 was used to construct the reference spectrum in the in-house library to identify the clinical isolates by MALDI-TOF MS. Additionally, N. dimidiatum PPC-216 and PLAB-055 strains were used to validate the in-house constructed reference spectra. Although four groups were observed in the dendrogram obtained from the proteins of each isolate profile, MALDI-TOF MS and sequencing results are in accordance, since all isolates were identified as N. dimidiatum.

Diagnóstico micológico: de los métodos convencionales a los moleculares / Mycological diagnosis: from conventional methods to molecular ones

Resumen: la incidencia de las infecciones fúngicas ha aumentado en las últimas décadas como consecuencia del incremento en el número de pacientes con factores predisponentes. Tanto el diagnóstico como el tratamiento de estas infecciones continúan siendo un reto para el personal de la salud. Aunque las especies de los géneros Candida, Aspergillus y Cryptococcus continúan siendo las más frecuentes, es notoria la emergencia de especies que no se habían reconocido anteriormente como patógenas para el hombre. Ante este panorama, el diagnóstico adecuado y oportuno de estas infecciones es de gran relevancia para la instauración de un tratamiento eficaz y, de esta manera, para impactar en la morbilidad y mortalidad que suelen causar algunas micosis, principalmente en los individuos inmunocomprometidos. Con esta revisión se pretende mostrar de manera general aspectos clínicos, epidemiológicos y, principalmente, relacionados con el diagnóstico de las infecciones fúngicas más frecuentes, partiendo de los métodos convencionales hasta las técnicas moleculares que actualmente se tratan de implementar en busca de un la prueba estándar de referencia que pueda superar la sensibilidad, la especificidad, la rapidez y el costo-efectividad de los métodos que se han utilizado hasta ahora en el diagnostico micológico.

Abstract: fungal infections incidence has risen in recent decades due to the increase of many predisposingfactors. The diagnosis and treatment of such infections continue to be a challenge for clinicians. Although some species of the genus Candida, Aspergillus and Cryptococcus remain as the most frequent, have emerged more fungal species not formerly recognized as pathogenic. Therefore, there is an increasing need for an appropriate and quick diagnosis of such infections in order to start an effective treatment and thus to impact on morbidity in the majority of patients and on mortality in the immunosuppressed. This review focuses in clinical and epidemiological features, but also in the diagnostic of most common fungal infections, based on conventional methods and new molecular techniques to search an standard test that be to more sensitive and specific, faster and cost-effective.